Guidelines for Coding Exit Routines

You can supply VSAM exit routines to do the following tasks:

Analyze logical errors
Analyze physical errors
Perform end-of-data processing
Record transactions made against a data set
Perform special user processing
Perform wait user processing
Perform user-security verification.

VSAM user-written exit routines are identified by macro parameters in access methods services commands.

You can use the EXLST VSAM macro to create an exit list. EXLST parameters EODAD, JRNAD, LERAD, SYNAD and UPAD are used to specify the addresses of your user-written routines. Only the exits marked active are executed.

You can use access methods services commands to specify the addresses of user-written routines to perform exception processing and user-security verification processing.

Related reading:

For information about the EXLST macro, see z/OS DFSMS Macro Instructions for Data Sets.
For information about exits from access methods services commands, see z/OS DFSMS Access Method Services Commands.

Table 1 shows the exit locations available from VSAM.

Table 1. VSAM user-written exit routines
Exit routine	When available	Where specified
Batch override	After you issue an IDCAMS SHCDS PERMITNONRLSUPDATE command while backout work was owed	IGW8PNRU exit in LINKLIB or LPALIB
End-of-data-set	When no more sequential records or blocks are available	EODAD parameter of the EXLST macro
Exception exit	After an uncorrectable input/output error	EXCEPTIONEXIT parameter in access methods services commands
Journalize transactions against a data set	After an input/output completion or error, change to buffer contents, shared or nonshared request, program issues GET, PUT, ERASE, shift in data in a control interval	JRNAD parameter of the EXLST macro
Analyze logical errors	After an uncorrectable logical error	LERAD parameter of the EXLST macro
Wait	For non-cross-memory mode callers using RLS	RLSWAIT parameter of the EXLST macro
Error analysis	After an uncorrectable input/output error	SYNAD parameter of the EXLST macro
User processing	WAIT for I/O completion or for a serially reusable request	UPAD parameter of the EXLST macro
User security verification	When opening a VSAM data set	AUTHORIZATION parameter in access methods services commands